Document sheet conveying apparatus

ABSTRACT

A document sheet conveying unit of the invention comprises a casing in which are mounted an active roller, a plurality of idle rollers, and at least a guide element. The idle rollers are mounted in a manner to be respectively in circumferential contact with the active roller. The guide element is mounted proximate to one of the idle rollers, and has a guide surface with a prolonged plane that is tangent with the corresponding idle roller at its contact point with the active roller. The guide surface thereby orients and guides the document sheet to adequately engage through the active roller and corresponding idle roller. Jam of the document sheet is therefore prevented.

BACKGROUND OF INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates generally to document sheet conveying unit and, more particularly, to a document sheet conveying unit that can reduce the occurrence of document jams.

[0003] 2. Description of the Related Art

[0004] A current image transmission and/or reproduction apparatus, such as a scanning machine or a facsimile machine, may include a document sheet conveying unit that conveys the document sheet to be processed, typically for capturing its image. When a great amount of document sheets has to be processed, this document sheet conveying unit may appear as an automatic document feeder for facilitating the use and improving the efficiency of the apparatus. This type of document sheet conveying unit is usually capable of automatically separating document sheets and individually conveying the separated document sheets through the sheet conveyance path. This sheet conveyance path further may respectively terminate in a sheet intake end and a sheet release end that are located on a same side of the unit to reduce its dimensional size.

[0005] Referring to FIG. 1, a schematic view illustrates a document sheet conveying unit known in the prior art. A known document sheet conveying unit 100 comprises, for example, a casing 110 in which are assembled an active roller 120 and idle rollers 130 a, 130 b, 130 c. The idle rollers 130 a, 130 b, 130 c are usually mounted along an inner surface of the casing 210 in a manner to be in circumferential contact with the active roller 120 for conveying a document sheet 10.

[0006] Via the above assembly, a sheet conveyance path 140 is defined, terminating in a sheet intake end 142 and a sheet release end 144 that are located on a same side of the unit 100. A document sheet 10 is introduced in the unit 100 through the sheet intake end 142, and is released through the sheet release end 144.

[0007] The unit 100 further includes an assembly of sheet-separating roller/plate 150, 152 placed proximate to the sheet intake end 142 before the active roller 120. The sheet-separating roller 150 is mounted in a manner to initially contact with the sheet-separating plate 152. Thereby, several document sheets 10 that reach the sheet-separating roller/plate 150, 152 can be individually separated and conveyed one by one through the active roller 120 and idle rollers 130 a, 130 b, 130 c. A sheet intake roller 160 is further mounted between the sheet-separating roller/plate 150, 152 and the sheet intake end 142.

[0008] As illustrated in FIG. 1, the introduction of the document sheet 10 is performed through the sheet intake end 142 via the sheet intake roller 160 that forwards the document sheet 10 through the sheet-separating roller/plate 150, 152. Thereafter, the document sheet 10 is conveyed along the sheet conveyance path 140 through the active roller 120 and idle rollers 130 a, 130 b, 130 c to the sheet release end 144.

[0009] While the document sheet 10 is conveyed along the sheet conveyance path 140, jam problems may occur. The conveyed document sheet 10 is likely to jam at curved portions of the sheet conveyance path 140 such as the location of the idle roller 130 b. This is typically due to an inadequate orientation of the front end of the document sheet 10 that, therefore, improperly reaches the idle roller 130 b at the point “b”, which produces its jam.

SUMMARY OF INVENTION

[0010] An aspect of the invention is therefore to provide a document sheet conveying unit that can prevent the jam of document sheets inside the conveying unit.

[0011] To accomplish the above and other objectives, a document sheet conveying unit of the invention comprises a casing in which are mounted an active roller, a plurality of idle rollers, and at least a guide element. The idle rollers are mounted in a manner to be respectively in circumferential contact with the active roller to convey the document sheet along a sheet conveyance path. The guide element is mounted proximate to one of the idle rollers, and has a guide surface with a prolonged plane that is tangent with the corresponding idle roller at its contact point with the active roller. The guide surface thereby orients and guides the document sheet to adequately engage through the active roller and corresponding idle roller. Jam of the document sheet is therefore prevented.

[0012] According to an embodiment of the invention, the guide surface of the guide element is planar. In a variant embodiment, the guide surface of the guide element is curved.

[0013] The sheet conveyance path terminates in a sheet intake end through which the document sheet is introduced in the conveying unit and a sheet release end through which the document sheet is released. A sheet intake roller and an assembly of sheet-separating roller/plate are further mounted between the active roller and the sheet intake end to respectively receive the introduced document sheet(s) and ensure that only one single document sheet is forwarded to the active and idle rollers.

[0014] It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,

[0016]FIG. 1 is a schematic view illustrating a document sheet conveying unit known in the prior art;

[0017]FIG. 2 is a schematic view illustrating a document sheet conveying unit according to an embodiment of the invention;

[0018]FIG. 3A is an enlarged view of the region P of FIG. 2, particularly illustrating a shape of the guide element; and

[0019]FIG. 3B is an enlarged view of the region P of FIG. 2, particularly illustrating a variant shape of the guide element.

DETAILED DESCRIPTION

[0020] The following detailed description of the embodiments and examples of the present invention with reference to the accompanying drawings is only illustrative and not limiting. Furthermore, wherever possible in the description, the same reference symbols will refer to similar elements and parts unless otherwise illustrated in the drawings.

[0021] Referring to FIG. 2, a schematic view illustrates a document sheet conveying unit according to an embodiment of the invention. As illustrated, the document sheet conveying unit 200 comprises a casing 210 in which are mounted an active roller 220, three idle rollers 230 a, 230 b, 230 c, and a guide element 270. A sheet conveyance path 240 is designed in the space defined between the active roller 220 and the inner surfaces of the casing 210. The idle rollers 230 a, 230 b, 230 c are pivotally mounted successively along an inner surface of the casing 210 in a manner to be in circumferential contact with the active roller 220. By the above assembly of the active roller 220 and idle rollers 230 a, 230 b, 230 c, a document sheet 20 is therefore conveyed along the sheet conveyance path 240 that passes between the active roller 220 and the respective idle rollers 230 a, 230 b, 230 c. The guide element 270 is fixedly mounted on an inner surface of the casing 210 proximate to the idle roller 230 b and peripheral surface of the active roller 220.

[0022] The sheet conveyance path 240 terminates in a sheet intake end 242, through which the document sheet 20 is inserted in the unit 200, and a sheet release end 244 through which the document sheet 20 is outwardly released. The sheet intake end 242 and the sheet release end 244 therefore are located on a same side relative to the active roller 220, which advantageously reduces the volume of the document sheet conveying unit 200 and may provide a more convenient handling for the user.

[0023] A sheet-separating roller 250 and a sheet-separating plate 252 are mounted inside the apparatus 200 close to the sheet intake end 242 and before the active roller 220. The sheet-separating roller 250 contacts with the sheet-separating plate 252, and has a peripheral surface provided with a sufficient frictional coefficient to separate one top sheet from several stacked sheets that lie on the sheet-separating plate 252. A single document sheet 20 is therefore ensured to pass through the active roller 220 and the idle rollers 230 a, 230 b, 230 c. A sheet intake roller 260 is further placed between the sheet-separating roller/plate 250, 252 and the sheet intake end 242 to forward an inserted document sheet to the sheet-separating roller/plate 250, 252.

[0024] As illustrated in FIG. 2, one or more document sheet 20, once having been inserted through the sheet intake end 242, is forwarded to the sheet-separating roller/plate 250, 252 by means of the sheet intake roller 260. After the sheet-separating roller/plate 250, 252, only a single document sheet is forwarded through the idle roller 230 a and the active roller 220 and, via the guide element 270, then is accurately directed to the idle roller 230 b. Ultimately, the document sheet travels through the idle roller 230 c to be finally released through the sheet release end 244.

[0025]FIG. 3A is an enlarged view of the region P particularly illustrating the guide element according to an embodiment of the invention. The guide element 270 has, for example, a triangular shape, and includes a guide surface 272, being planar in this embodiment, that extends along a direction B substantially parallel with the tangent line A to the rollers 230 b, 220 at the contact point “a”. When the document sheet 20 approaches the idle roller 230 b, the guide surface 272 reorients the front end of the document sheet 20 to adequately engage along the direction of the tangent plane through the idle roller 230 b and active roller 220. Therefore, jam of the document sheet due to an inadequate orientation of its front end, when reaching the idle roller 230 b, is therefore prevented. The guide element 270 can be either mounted on the inner surface of the casing 210 via known fastening methods such as screw fastening or adhesion, or formed with the casing 210 in a single body.

[0026] As illustrated in FIG. 3B, the guide surface 272 of the guide element 270 alternatively may be curved, in which case the prolonged direction A of its end edge is preferably tangential to the contact point “a”. The guide surface 272 thereby adequately guides the document sheet 20 along the tangential direction A to pass through the contact point “a”. Jam problems are therefore favorably prevented.

[0027] The guide structure 270 is placed proximate to the idle roller 230 b because jams are more likely to occur there. However, it will be understood that the guide element 270 may be also mounted proximate to other idle rollers where jam occurrences may be more likely to happen to provide the same advantages.

[0028] As described above, the invention therefore provides a document sheet conveying unit in which the document sheet is favorably conveyed through the roller assembly, reaching the idle rollers along their tangential direction. Jam problems are therefore prevented.

[0029] It should be apparent to those skilled in the art that other structures that are obtained from various modifications and variations of different parts of the above-described structures of the invention would be possible without departing from the scope and spirit of the invention as illustrated herein. Therefore, the above description of embodiments and examples only illustrates specific ways of making and performing the invention that, consequently, should cover variations and modifications thereof, provided they fall within the inventive concepts as defined in the following claims. 

1. A document sheet conveying unit for conveying document sheet, comprising: a casing; an active roller, mounted inside the casing; a plurality of idle rollers, mounted in the casing a manner to be in circumferential contact with the active roller to convey the document sheet along a sheet conveyance path; and at least a guide element, placed proximate to one of the idle rollers, the guide element having a guide surface that guides the engagement of the document sheet through the corresponding idle roller and active roller along the sheet conveyance path.
 2. The document sheet conveying unit of claim 1, wherein a prolonged plane of the guide surface is tangent with the corresponding idle roller and active roller at the contact point there between.
 3. The document sheet conveying unit of claim 2, wherein the guide surface is a plane.
 4. The document sheet conveying unit of claim 2, wherein the guide surface is a curved surface.
 5. The document sheet conveying unit of claim 1, wherein the guide element is formed with an inner surface of the casing in a single body.
 6. The document sheet conveying unit of claim 1, wherein the guide element has a triangular shape.
 7. The document sheet conveying unit of claim 1, wherein the sheet conveyance path terminates respectively in a sheet intake end through which the document sheet is introduced in the document sheet conveying unit, and a sheet release end through which the document sheet is released from the document sheet conveying unit.
 8. The document sheet conveying unit of claim 7, wherein the sheet intake end and the sheet release end are located on a same side relative to the active roller.
 9. The document sheet conveying unit of claim 7, further including the assembly of a sheet-separating plate and a sheet-separating roller in contact with the sheet-separating plate, the sheet-separating plate and the sheet-separating roller being placed on the sheet conveyance path between the active roller and the sheet intake end.
 10. The document sheet conveying unit of claim 9, further including sheet intake roller mounted on the sheet conveyance path between the sheet intake end and the assembly of the sheet-separating plate and sheet-separating roller. 